Stoker alarm and control



Jan. 3, 1950 A. B. NEWTON 2,493,591

STOKER ALARM AND CONTROL Filed May 27, 1946 m v INVENTOR.

ALw/N B. NEWTON M 14% A W,

Patented Jan. 3, 1950 ZAQBZSQE STOKER ALARM AND CONTROL Alwin B. Newton, Oakwood, Ohio, assignor to Chrysler Corporation, Highland Park, Mich., a

corporation of Delaware Application May 27, 1946, Serial No. 672,496

2 Claims.

My present invention relates to a mechanism for operating a feed screw for a coal stoker or similar device.

In a coal stoker of the rotating screw type it quite often happens that some foreign substance such as bolts or other pieces of metal, rocks or pieces of wood are accidentally included in the coal supply and the feeding mechanism becomes jammed thereby. In such case means must be provided to protect the motor from being burned or other parts from becoming broken, and an alarm device is desirable to call attention to the existing condition before the fire extinguishes itself. An object of my invention is to provide a rotating feed screw stoker or the like with means for stopping the application of driving torque when the screw becomes jammed, in combination with means to sound an alarm mechanism as long as the screw remains jammed.

A further object of my' invention is to provide means having the foregoing characteristics of such nature that the driving force will be automatically reapplied as soon as the obstruction is removed. The latter feature is of particular advantage since an obstruction quite often clears itself as soon as the driving torque is relieved; hence the present invention is particularly useful in that if the obstruction should clear itself normal operation will be resumed, thus providing further chance that the stoker will function in normal manner regardless of the presence or absence of an attendant.

The foregoing and other objects and advantages of my present invention will be apparent from the following specification taken in connection with the accompanying drawings.

In Fig. 1 a stoker feed driving mechanism made in accordance with my invention is shown partly in elevation and partly in section, and certain parts of the construction are schematically illustrated; and

Fig. 2 is a section on the line 2-2 of Fig. 1.

The invention is illustrated as comprising a casing l within which is journalled a shaft II which may comprise a screw feeding device attached thereto through suitable connecting means (not shown). The shaft II is driven by a driven worm wheel l2 which is rotated by a driving worm gear l3. The gear 13 is fixed to a floating shaft l4 journalled in a box 15 and a removable bearing l6 carried by an opposing portion of the casing ID. The shaft M is rotated by a pulley adapted to be driven through means of a belt (not shown) by a motor 2 I. Other forms of connecting mechanism may cause the motor 2| to rotate the shaft Hi. When the shaft I4 is rotating and driving torque is being transmitted from the threads of gear l3 to the teeth of wheel I2 the floating shaft l4 will be forced toward the right so that a collar 22 thereon will engage a thrust bearing 23 retained against the end of the boss I5. If on the other hand the shaft I I should be prevented from rotation while the gear l3 continues to rotate, the gear will feed itself back toward the left, such movement being permitted by longitudinal movement of the shaft 14. I have thus provided means for limiting the movement of the shaft in one longitudinal direction when the screw is being rotated and means whereby the shaft may move in the opposite direction if the screw should be prevented from rotating and thus causes the worm gear to back away from normal position.

In order to stop the motor 2| shortly after the screw is prevented from rotating I provide a motor switching device as follows: A collar 25 on shaft 14 engages a portion of a forked lever 25, the legs of which straddle the shaft. The lever 26 is provided with a lower fulcrum tip 21 bearing against a portion of the wall of the casing l0 and supported in position by a lug 28 extending from the wall. The upper end of the lever engages a lug 29 extending from the top of the casing and the lever is retained in such position by a movable fulcrum member 30 journalled in a boss of the wall of the casing. The member 30 is forced toward the right by a spring 3| adjustably compressed thereagainst by a plug 32. A contact 33 carried by the upper end of the lever engages a spring contact 34 carried by the lug 29 when the lever is in position as shown and the screw is being rotated. The contacts 33 and 34 complete a circuit to the driving motor 2| from power lines 35 and 3B. As long as power is being supplied to the motor under control of suitable thermostatic or other controls (not shown) and contacts 33 and 34 remain in engagement, the shaft II will be rotated to cause feeding of coal to the fire. If the worm gear l3 should be backed away from normal position sufliciently to separate contacts 33 and 34 the motor 2| will stop. If the release of pressure against the obstruction when the motor stops causes the obstructing matter to drop from obstructing position the spring at is designed to have suflicient strength to shift the lever 26 back to reengage the contacts 33 and 34 and cause resumption of movement. Such suitably insulated from conductive portions o'fthe casing. The lever 26 also carriesrajpad of insulation 3%;) adapted to engage the. inner end -of a rod 4| pressed against the pad by a spring 42. The

outer end of the rod M formsa switch bridge, 43

adapted to complete a circuit from'a' contact plate 44 to a spaced contact plate 45 carried ontinsulating blocks attached to the wall of the casing l6.

Plate 46' is 'attachedtoua wire 4Bcandp1ate45 to a wire 41 completing a circuit to analarm bell 48 drawing power from-a suitable portionnofthe circuit suchas represented by transformer 48. When lever' 26 is shifted by disengaging movement of theworm gear I 3 the bridge 43 completes the circuit to the-alarm bell to thus .notify an attendant that attention should be given to the Stoker. If the stokerclears-itself the alarm bell will cease sounding. Other-forms of circuit completing devicesima-ybe substituted .for that illus- 'trated, and the "alarmbell-may: derive power from other suitable sources without departingtfrom the spirit of my invention.

In the operation of my invention the shah; H will be rotatively driven-tocause the .feed screw or the like to, supply-coal to a retortinaccordance with anypf the usual-mannera If the feed screw or the-alike should become blocked; the floating shaft will back away from its .normal position,

"thus causing thedrivingmotor to be disconnected from the source of power and. simultaneously causing an alarmto be sounded. Iflthebbstruction should :clear itself the worm gear will be automaticallymoved-back toenormaledriving position, the motor will resume .dr-iiv'ing. action-and the alarm bell willcease sounding Having illustrated and described a preferred embodiment of m-y-inventionit should'be apparent 'to those skilled in the art that modification in detail and arrangementthereof are permissible withoutdeparting tromthe spirit of my invention. I- claiin-ail-suchmodifications. ascome within the scope of thefollowingclaims:

lpln a' coal stoker of thetype having .a rotating screw for feeding the coal, a driven worm wheel for transmitting torque to said screw, a :driving 4 worm gear for transmitting torque to said worm wheel and having a normal operative position in engagement with said worm gear, a floating shaft carrying said driving worm gear, journal means supporting said shaft for rotative movement and permitting longitudinal movement thereof, a motor for driving said shaithmeansilimiting the movement of said shaft in @One longitudinal direction when said screw is being rotated, yieldable means urging said shaft toward said limiting means, and switch means operated upon movement of :saidyieldable means to stop said motor if the screw should be prevented from rotating and said worm .gear, backs away from said normal position,.said yieldable means being operable to close said switch means if the obstruction pre-' venting rotation of the screw should be removed.

2. In-a coal stoker of the type having a rotating screw for feeding the coal, a driven worm wheel for. transmitting torque-- to said screw, a driving Worm ,gear for'transm-itting"torque to-sa'id worm wheel and havinganormal operative position engagement with said Worm gear, a fl'oating s'haft carryingsaid driving worm' gear, {journal means supporting said shaft for rotaitive movement and permitting longitudinal movement thereof, :a motor for drivihgsaidshaft, meanslimitingthe movement of said-shaft in one longitudinal direotion when said screwis being rotated; yiel'da'ble means urging saidshaft towardsaid limiting means, and switchmea-ns operated upon-movement of said yieldable'means to stop said motor if the screw should --be prevented from rotating and said worm gear backs away'from said :normal positiomsaid yieldable means compri'singapivotally mounted lever, -spr-ing means t-hrusting against said lever at a point remote frem the fulcrum defin-odbytho pivotaPmou-nting of said lever and means 'associatedwithsaid shaft and engaged by saiidlever atza-point' betweensaid fulcrum and said 'spri'ngmeans whereby a mechanical' advantage 'is provided to facilitate the-return of saidshait' to its norm-al position by said spring as an incident to' removal of :said obstruction. r

preparationsorral):

The following references are of :recordin-the file of this patent;

UNITED STArns .BA'IENII'S- 2,3 17,490 Simpson Apr. 27., 319143 

